The present invention relates to a process for producing high polymerization degree polyetheresteramides in a short time without causing any such troubles as gelation, color tone decrease and haze increase in the course of polycondensation.
An art of synthesizing polyamide elastomers by obtaining polyetheresteramides through the ester interconnection of poly(alkylene oxide) glycols by amide forming components and dicarboxylic acids has been developed and established as their industrial production process. It has already been disclosed in U.S. Pat. Nos. 4,230,838, 4,331,786, 4,332,920 and 4,207,410 as well as Japanese Laid-Open Patent Gazette No. 90017/1982 that tetraalkyl titanate and other titanium catalysts are effective for the polymerizing production of the polyetheresteramides. However, they do not sufficiently increase polymerization degree and increase polymer haze because they are readily inactivated by the water generated in the course of polymerization. If they are used in great quantities, therefore, they cause the troubles of generating gelated materials, decreasing color tones or reducing the heat resistance of the polymers. Their application quantity is therefore limited. Further, tetraalkyl zirconate and zirconium catalysts has been proposed among highly-active ones (U.S. Pat. No. 4,252,920). They, however, pose a serious problem of readily generating gelated materials. As described heretofore, the conventional catalysts used to produce the polyetheresteramides are not always satisfactory in this respect.
The inventors have studied the catalysts for obtaining high polymerization degree polymers in a short time without causing such troubles as gelation, color tone decrease and haze increase in the course of polycondensing production of the polyetheresteramides and found out that organic tin compounds and antimony oxides show very high polymerzation catalyzing activities and do not generate gelated materials.
Tin compounds and antimony oxides contribute to the production of the polymers satisfactory in both performances and quality. It has, however, been learned as necessary to ameliorate the yellow and grey tones given to the former and lattre respectively in some cases when the polymers are used for textiles and other colored goods, apart from the general industrial use.
In this connection the authors have attempted to decrease the ratio of the addition of tin and antimony catalysts and change its timing and studied what copolymer composition ratios readily generate color tones. Nevertheless, almost all the methods attempted and studied have not been effective in this respect. However, they have found that the systems obtained by mixing antimony oxides and organic tin compounds at specific ratios unexpectedly cause further increase in polymerizing activity and can produce nearly colorless, transparent polymers and worked out the present invention.